A blow dryer for drying and styling hair normally has a housing formed with a large head and a slim handle. Inside the head is provided a fan which draws air in through an inlet on one side of the head and expels it through a nozzle on the other side of the head. A heater is normally provided in the flow path through the dryer head downstream of the fan. Thus cool air is drawn in through one side of the head, heated, and expelled from the other side.
In order to insure that the output air is of uniform temperature it is normally considered necessary to provide a relatively long nozzle on the outlet. The heated air, some of which has usually been heated to a much higher temperature than the rest, therefore has a chance to mix inside the nozzle to equalize its temperature. When an attempt is made to shorten this nozzle to make the dryer as compact and light as possible, the user will often find that a certain part of the air stream is much hotter than another. In fact one portion of the air stream can be so hot as to damage the user's hair, a common risk run by the user of a blow dryer.
Another disadvantage of the known systems is that the inlet openings, through which the air is aspirated, often can draw in loose strands of hair, and also frequently aspirate airborne chemicals being used to treat the hair. Thus the user might have his or her hair drawn into the blower and pulled out, a highly unpleasant experience, while at the same time the fan inside the blower becomes dirty with hair fragments and miscellaneous chemicals.